Electrical contact means



Patented Sept. 21, 1954 UNITED STATES PATENT OFFICE Stockholm,

and Anders Ossian J r'irgensen,

Traneberg, Sweden, assignors to Telefonaktiebolaget L M Ericsson, Stockholm, Sweden, a

company of Sweden Application June 3, 1952, Serial No. 291,384

Claims priority, application Sweden June 6, 1951 15 Claims.

The present invention refers to contact or switch means for closing or breaking electrical circuits, more particularly to contact means in which flat springs are fastened at one of their ends, the other end of the springs being movable into contact with a stationary contact in form of a contact spring or a rigid contact by means of a lifting pin and an operating member. Such fiat springs are relatively long, and the necessary space is not always available. The present invention relates to contact means with shorter contact springs and which permit to adjust the contact distance and the contact pressure by changing the lever relation effective upon operation of the contact springs. The point of contact can usually not be changed, and no useful solution of the problem how to change the point of engagement of the lifting pin by adjustment has been found prior to this invention though the problem has existed for a very long time.

According to the invention a variable lever relation is obtained by arranging a support for the movable contact spring at the middle of the contact spring, a flexible contact strip and a lifting pin at one end of said contact spring and an operating member which, by means of said lifting pin, causes the contact spring to pivot as a double-armed lever with said support as fulcrum and to make contact with a rigid contact or contact spring at its other end. Said support can easily be made movable.

The invention will be described more closely below with reference to the accompanying drawings, Figs. 1-6.

Figs. 1, 3 and 6 show different embodiments of a movable contact spring according to the invention.

Figs. 2 and show two applications of the invention to telephone relays.

Fig. 4 shows a rigid contact spring for a relay according to Fig. 5.

The contact spring according to Fig. 1 consists of two main parts In and lb, of which la is the contact spring proper and lb is a flexible connection strip, one end lc of which is intended to be rigidly fixed to a contact block or the like and is provided for this purpose with a soldering lug Id.

In Fig. 2, two contacts springs I made according to Fig. 1 and arranged in a spring assembly are shown. The strips lb of the springs are secured by means of two screws ll between insulating plates 9 together with two stationary contacts l0 and an operating spring 2. The entire contacts assembly is mounted on a yoke 6 of an electromagnet 8. The strips lb of the springs l which are inserted between plates 9 are bent so as to be biased upwardly but are kept pressed down by engagement with the operating spring 2 and the pin or bar 4 with the tooth 3. This bar is connected to armature 'l of the magnet for movement in unison with the armature. The part la. of the contact springs l is supported at its middle by the support 5, which is adjustably secured by means of a screw l3 to the yoke 5 of the electromagnet 8. When the electromagnet 8 actuates its armature l, the spring 2 is lifted by means of the bar 4. The end of the contact springs I further to contacts l0 follows the spring 2 and tooth 3 upwards due to its bias, whereas their near end moves downwards and makes contact with the rigid contacts Hi. When the electromagnet releases its armature, the spring 2 presses down the further end of the contact springs I by means of the tooth 3. The near end of the contact springs l is now lifted and the contact between the contact springs Id and ll! is broken.

The components l, 5 and 9 are naturally made of electrically non-conducting material.

The electromagnet 8 has a core 8a, one end of which is clamped between a clamp 61) by means of a screw l2. The clamp 6b with its protruding part 6a for fastening a relay is made in one piece with the yoke 6. When the screw I2 is released the electromagnet 8 can be displaced lengthwise, whereby the air gap between the armature l and the core of the electromagnet maybe adjusted. The play of the armature l is adjusted by means of the screw ll,,which is threaded in the yoke 6, and passed through a hole in the armature l, which when attracted abuts against the head of the screw l'l.

When the screw I3 is unfastened the support Scan be moved along the springs l, whereby the screw l3 slides in a slot 50,. In this way the contact distance and the contact pressure between the springs l and the contacts lll may be adjusted. The contact spring according to Figs. 3 and 6 consists of a part m. which is the contact spring proper, a part lb, the connecting contact strip and a part lc for fastening. It also comprises a soldering ear Id. Fig. 4 shows a rigid contact spring ID with soldering ear Illa for a relay according to Fig. 5. r

In Fig. 5 two contact springs according to Fig. 3 cooperate with two rigid contact springs according to Fig. 4 by means of two screws H in a spring holder 9 fixedly secured to the yoke 6 of the electromagnet 8. The contact springs I rest against a support 5, which is. adjustably fixed to the yoke 6 by means of screw l3. When the screw 13 is unfastened, the support can be displaced along the springs I, whereby the screw l3 slides in the slot 50.. By means of a pin or bar 4 the further end of the springs I can be lifted, the near end moving downwardly and making contact with the stationary contact springs I0. The rib 4 is passed through a hole in the yoke 6 and directly operated by the armature l of the electromagnet.

The armature I is fixed to the yoke 6 by means of a leaf spring l5 and a screw 16. The spring 15 is fastened to the armature l by means of the screw I6 and rests on two lugs Bet on the yoke 6. By means of the screw It the tension of spring l5 can be changed so that the load of the armature is varied.

The electromagnet 8 is adjustably fastened to the yoke 6 by means of a screw M, which can be moved in a slot 15. The leverage exerted by the magnetic field impressed on the armature I can thereby be varied independent of the variation of the length of the levers on the contact springs I, which can be effected by moving the support 5.

The relay may be fastened by means of screws through two threaded holes in the yoke, one of which, 60, is seen in Fig. 5.

We claim:

1. An electric contact means for making and breaking contact between electric circuit connections comprising in combination a stationary contact, a movable contact in form of a contact spring, a support means engaging and supporting said contact spring at an intermediate point thereof for forming a two-arm lever, the point of engagement of the contact spring with the support means constituting the fulcrum of said lever, yieldable means coacting with said contact spring and biased to urge one end of the contact spring toward a position in which the other end of the contact spring is in engagement with said stationary contact, liftable retaining means engageable with the said one end of the contact spring and holding the said end in a position in which the other end of the contact spring is disengaged from the stationary contact, and actuating means coacting with the retaining means for lifting the latter into a posi- 5-.

tion in which said yieldable means are released for urging the respective end of the contact spring into its contact-making position.

2. An electric contact means for making and breaking contact between electric circuit connections comprising in combination a stationary contact, a movable contact in form of a contact spring, a support means engaging and supporting said contact spring at an intermediate point thereof for forming a two-arm lever, the point of engagement of the contact spring with the support means constituting the fulcrum of said lever, yieldable means coacting with said contact spring and biased to urge one end of the contact spring toward a position in which the other end of the contact spring is in engagement with said stationary contact, liftable retaining means engageable with the said one end of the contact spring and holding the said end in a position in whch the other end of the contact spring is disengaged from the stationary contact, and electro-magnetic means including a movable armature operatively coupled with said retaining means for lifting the latter into a positon in which said yieldable means are released for 4 urging the respective end of the contact spring into its contact-making position.

3.. An electric contact means according to claim 1, wherein the said liftable retaining means comprising a bar having thereon a protrusion engageable with the said one end of the contact spring for retaining the contact spring in the position in which the other end thereof is disengaged from the stationary contact, the said actuating means being operatively coupled with said bar for axially lifting the same upon actuation of the actuating means to free the said yieldable means for the purpose aforesaid.

4. An electric contact means according to. claim 3, wherein the said yieldable means comprise a flexible strip fixedly mounted at one end and operatively connected at the other end with the said one end of the contact spring, the said flexible strip being biased to flex the said contact spring end toward a position in which the other end thereof engages said stationary contact.

5. An electric contact means according to claim 4 and further comprising a stationarily mounted flexible member secured to said bar for biasing the latter into a position in which the protrusion thereon retains the contact spring in a position in which the respective end thereof is disengaged from the stationary contact.

6. An electric contact means according to claim 1 wherein the said support means is mounted for movement relative to the length of said contact spring for varying the location of said fulcrum and hence the relative length of the lever arms formed by said contact spring.

7. An electric contact means according to claim 6, wherein the said support means comrises a laterally notched bar, the said contact spring being slidably fitted in the notch of said bar for forming said fulcrum, and wherein adjustable mounting means support said notched bar for displacement thereof parallel to its plane.

8. An electric contact means according to claim 1, wherein the said contact spring and the said yieldable means are in form of a unitary flexible strip of substantially U-shaped configuration, one arm of said strip forming said contact spring and the other said yieldable means.

9. An electric contact means according to claim 8, wherein the free end of the strip arm forming said yieldable means is fixedly held, the said arm being flexed to bias the other strip arm forming the contact spring toward the position in which the free end of said latter arm engages said stationary contact, and wherein the said liftable retaining means are engageable with the bight joining the arms of said strip, the said support means engaging an intermediate point of the strip arm forming said contact spring.

10. An electric contact means according to claim 9, wherein the said fixedly held end of the respective arm of the flexible strip and said stationary contact are supported by a common post made of insulation material.

11. An electric contact means according to claim 1, wherein the said stationary contact and the said yieldable means are supported on a common support means made of insulation material.

12. An electric contact means for making and breaking contact between electric circuit connections comprising a plurality of stationary contacts mounted one above the other and a corresponding plurality of movable contacts mounted one above the other, each of said movable contacts being in form of a contact spring coacting with the respective one of said stationary contacts, a common support means engaging and supporting each one of said contact springs at an intermediate point for forming a plurality of twoarm levers, the point of engagement between the common support means and the respective contact spring constituting the fulcrum of the lever formed by the said spring, a plurality of yieldable means, one for each contact spring, each coacting with the respective one of said contact springs and biased to urge one end of the respective contact spring toward a position in which the other end of the said spring is in engagement with the respective stationary contact, common liftable retaining means engageable with the said one end of each of said contact springs and holding the said one end in a position in Which the other end of the contact spring is disengaged from the respective stationary contact, and common actuating means coacting with said retaining means for lifting the latter into a position in which all said yieldable means are released for urging the respective ends of the contact springs into the said contact-making position.

13. An electric contact means according to claim 12, wherein the said common support means are mounted movable along the length of said contact springs for simultaneously varying the fulcrum points of all the contact springs.

14. An electric contact means according to claim 12, wherein the said liftable retaining means comprise a bar having thereon a plurality of axially spaced protrusions each engageable with the respective one of said yieldable means for retaining all the yieldable means in the aforesaid position.

15. An electric contact means according to claim 14, wherein the said contact springs and the said yieldable means are each in form of a unitary flexible strip of substantially U-shaped configuration, one arm of each strip forming the respective contact spring and the other the respective yieldable means.

References Cited in the file 01 this patent UNITED STATES PATENTS Number 

